This invention relates generally to the art of toilet flush systems and more particularly to dual-flush valve systems of the type through which two different flush volumes of water may be released in order to evacuate a toilet bowl. In an effort to conserve water many varible toilet flush systems have been developed, but very few have required only one handle for such flushes.
One such single handle for dual flushes is disclosed in U.S. Pat. No. 4,504,984. This patent discloses a single flush lever attached to two flush valves. A partial or full flush is effectuated by a partial or full depression of the handle, thus requiring the user to regulate the manual force he applies to the handle.
U.S. Pat. No. 4,175,295 describes a system whereby the user has the option of either rotating the handle in one direction for a light flush or the opposite direction for a heavy flush. But the positioning of a single internal lever is biased by a pair of springs which are subject to wear and stretching.
Other single handle, dual-flushing systems have been proven to be functionally unreliable and to require of the user a non-traditional means of flushing.